Quoting LongHauler (Reply 1):Usually the the main structure and strength of the aircraft is compromised.

Indeed....

CO had a 777 suffer a pretty bad tailstrike last year which required Boeing to come in and make the repairs. Apparently the entire tail of the aircraft was removed so that the rear galley was visible. Boeing was very strict about having no pictures taken as well...

Yeah, anything less than severe structural damage can be accomplished using inhouse resources. It may require bringing in expertise or specifically tasked teams (sheetmetal/composites, engine change crew, etc) for field service, but most larger airlines have the skills within the company. Smaller operators may have to contract to larger airlines (UA Services as an example) to get those serious problems fixed.

Quoting LongHauler (Reply 1):Usually the the main structure and strength of the aircraft is compromised.

I would not agree with this statement.

The aim of the Structural Repair Manual is to provide repair data and instructions to restore the airplane to original strength. There are times when the manual limits the repair and then says "Contact Boeing..." Even in those cases, Boeing can provide repair instructions and an 8110-3.

We have replaced major structural elements of the aircraft, such as the FS 820 fittings on the 707, lower 41 on 707s, rear spar chord on a 727, tail strikes on 757s. I remember having Douglas sent a team to replace the trunion fitting on a DC-8, after observing, we did it ourselves after wards.

It is a matter of data and resources. Obviously the manufacturer will have a field engineer when the damage is significant that can have several engineers available to assist in the matter. Also bringing in the manufacturer's team costs BIG BUCKS!

If it is a recovery, the manufacturer has teams and is better suited to recover an airplane than a repair station or an airline.

NWA had a MLG tire on a DC-10 come apart in Bombay a few years ago. It took out the flap and a good part of the wing structure in the flap area. Boeing went in and fixed that. And NW changed their tire requirements for MLG's.

They had a similar thing with an Airbus- crew misread the T/O trim settings A/C thumped the compass rose at DTW pretty hard. From the outside it didn't look too bad- opened the aft compartment and found it was almost mortally wounded, floor beams broken, stringers twisted, just lots of bad things. They had Airbus come fix that one.

Sometimes MRO's can write their own repair instructions if they are authorised by the local authorities. For instance Air Canada sometimes did repairs when the damage was outside limits of the SRM, but justified by comparison etc. In most cases this was done and additional/more frequent inspections demanded and the damaged repaired at the next major check.

Quoting TimT (Reply 5):Sometimes MRO's can write their own repair instructions if they are authorised by the local authorities

In my own experience, I have found that the airline engineers are more and more moving away from from this, and letting BACO take the responsibility. I'm not sure if it's lack of experience and knowledge on the engineers part, or their managers/company that don't want to shoulder the responsibility. We used to have engineers that would write repair specs period, then we had repair specs that would require BACO approval (sometimes these would end up being permanent, sometimes good for a time limit, ie. next c-ck), then we had to get BACO approval up front. I also experienced repairs (such as limits on boring T/R hinges to clean up corrision) that were once approved, no longer being approved. I think a lot of this has to do with liability .

the job is to big when the company/airline decide its to big. Damage to an aircraft may not have a repair in the SRM, this does not mean that they get the manufacturer in to repair it, it means you need to get the manufacturer to approve a repair scheme which you can then perform.
Your companys maintenance control communicate with the big chiefs to decide wether a job is to big.

Quoting Corey07850 (Reply 2):CO had a 777 suffer a pretty bad tailstrike last year which required Boeing to come in and make the repairs. Apparently the entire tail of the aircraft was removed so that the rear galley was visible. Boeing was very strict about having no pictures taken as well...

There are a couple of pictures on CO's Tech OP's web site but I would get into some serious s*** if I linked the pic's here. Sorry. You're right it was a big job the entire 48 section (major zone 300) was removed to facilitate replacement of the aft pressure bulkhead. The entire tail was suspended from an overhead crane with the vertical stabilizer removed.

Three years ago CO was involved in the 737-500 EGPWS pilot project modification. The very first -500 EGPWS was accomplished here in MCO. As an avionics tech I was heavely involved in re-wiring the aircraft.

We had engineers and test pilots from Boeing, Rockwell/Collins engineers, FAA rep's, and CO engineers. Basically the job entailed conversion from VOR/ILS recievers to MMR's. Installalation of GPS antenna's. Replacement of the old GPWS system to the EGPWS system. Many other systems required modification also, the IRS, EFIS, autopilot, and FMS all had to be modified. The project took three weeks to complete. It was by far the biggest job I have been involed in to date.

An improper jacking on a 744 at LH maintenance caused the 747 to bend and wrinkle behind the wing, LH built a jig to hold the tail of the 747 and fixed the 747 by removing the damaged part and replacing it with a new section.
An Boeing rep came over to oversee the operation and was impressed that Boeing offered LH an contract for aircraft crash restruction, but LH turned it down.